1. Field of The Invention
This invention relates to novel topical anesthetic compositions containing high concentrations of benzocaine in a micronized powder form. More particularly this invention relates to novel anesthetic compositions for topical administration having a smooth feeling when applied to the skin and remaining smooth after drying and comprising an emollient vehicle having suspended therein micronized benzocaine.
2. Description of Related Art
An aerosol anesthetic composition comprising high concentrations of benzocaine is described in U.S. Pat. No. 4,600,575. That patent and the patents discussed therein, particularly U.S. Pat. No. 4,052,513, all disclose benzocaine compositions wherein the benzocaine is dissolved in a suitable solvent and incorporated into an aerosol system or incorporated into an ointment, lotion, spray, gel, etc. As explained in patent 4,600,575 increasing the concentration of benzocaine, however, had to be balanced against the increasing probability of benzocaine precipitation, particularly at low temperatures. Benzocaine precipitation forms relatively large crystals which, when formed in situ in an ointment or lotion, for example, produce a gritty feeling when applied to the skin, or clog spray equipment when incorporated in a spray.